This invention relates to dynamoelectric machines; and, in particular, to dynamoelectric machines of the type including a rotor having electrically conductive windings disposed in a plurality of axially extending slots. Furthermore, this invention relates to a plurality of subslot covers which are joined end to end to extend in the axial direction so as to be approximately coextensive with the dynamoelectric machine slot.
A dynamoelectric machine includes a rotor body having a plurality of axially extending slots into which electrical windings are inserted. The rotor body is generally formed of a steel material whereas the rotor windings may comprise a plurality of electrically insulated copper wires. In a direct-cooled dynamoelectric machine each slot may further include an axially extending subslot for ventilation and cooling. The direct-cooled machine is one which is cooled directly by the atmosphere in which it is disposed, e.g., air or hydrogen. The subslots are part of a ventilation scheme, known in the art, for transferring gas coolant axially along the rotor. Each slot also includes provision for the radial flow of gas coolant primarily through ventilation slots in the windings.
In the aforementioned dynamoelectric machine, it is necessary to further electrically insulate the rotor windings from the rotor body, such insulation taking the form of non-conductive "slot-armor". One such insulation is shown in U.S. Pat. No. 4,321,498 issued Mar. 23, 1982 to Vogt and assigned to the assignee of the present invention. In that patent, herein incorporated by reference, it is suggested that a preferred embodiment of the invention would include a pair of electrical insulating members (slot armor), each member having a radially extending portion terminating in a base leg, the electrically insulating members disposed in each slot so that the radially extending portions are adjacent opposite walls and the base legs extend towards one another. In addition, there is an axially extending subslot cover having opposite sides formed with axially extending grooves for accepting therein each opposite base leg, of the electrical insulation members, whereby an interlocking joint is formed between the subslot cover and the insulating slot armor.
In U. S. Pat. No. 4,560,896 issued on Dec. 24, 1985 to Vogt and Derderian, and assigned to the assignee of the present invention, a slot armor comprising axially and radially extending sidewalls joined together by a radially inner, axially extending base portion to form a "U" shaped channel is positioned by a subslot cover having a planar outer member and a planar inner member. The slot armor is formed with spaced apart holes which allow the inner and outer members to be bonded to one another as well as to the slot armor positioned therebetween. Ventilation slots are thereafter machined into the slot armor subslot composite.
In U.S. Pat. No. 4,633,116, issued on Dec. 30, 1986, to S. K. Derderian and also assigned to the assignee of the present invention, a plurality of individual subslot covers are joined together, end to end in the axial direction, to be approximately co-extensive with the generator rotor slot so that when assembled with the proper insulation in the slot, the generator windings are insulated from the rotor itself. In that patent, it is further disclosed that each subslot cover has a radially inner first portion adjacent the subslot whereas a radially outer second portion is co-extensive with the first portion. Adjacent first portions are joined together at an interlocking joint and the radially outer second portion is secured to its respective inner portion. The radially outer second portions are butted together to form a continuous cover. FIG. 2 of the patent most clearly shows the aforesaid construction.
It is an object of the invention to provide an improved slot armor of the type including a plurality of subslot covers latchably secured to one another in an end to end configuration.
It is also an object of this invention to provide an improved securement at each end of individual subslot covers.
It is a further object of this invention to provide an upper or radially outer member for interconnecting adjacent subslot covers.
It is another object of the invention to provide improved electrical creepage resistance in a subslot cover construction.